GT doesn't need an open world "Free Roam" anyway. That's not what this game is about.
Then you sir are definitely playing the wrong game. It's been the same since GT1, what makes you think they'll change it now?
Kaz himself mentioned they were looking into (or were already developing) a 'traffic-mode' at the time GT5 was just released (remember some of those early demos where the cars had indicator icons in the HUD?), showing the concept of what constitutes a GT-game isn't set in stone even though the basic structure of the game has indeed not changed since GT1,
yet.
Should what the GT-series 'are about' be defined by how it was or is right now or should they (hypothetically for now, given resource/time constraints) be allowed to expand in scope? (within its own context and not losing what it currently offers).
For me, the GT-series (and Forza, even though I've never played it) are foremost a celebration or hommage to cars and car-culture before anything else and racing is only one (a vital and important one obviously) aspect of that.
That's the context (which is a relatively broad context) I use when I express liking the idea of free roam, just driving cars offline and online on
more than just closed racing tracks.
Not free roam in the sense of a true sandbox game or the more driving-orientated but mission-based Driver SF for example, but to simply make more use of the wide variety of cars included (cars tend to be driven mostly on public roads, why not in a driving simulator?).
I love racing on closed tracks or try to reach certain goals in the game but if I just want to drive a car in a casual way, without any goal, on a road I haven't driven before, I'm currently limited to making endless variations of a course creator theme which is yet another closed track I get to know eventually (or have to regenerate) and even a point to point option isn't a solution to that, nevermind that you can't choose another direction.
Does GT need free roam? That depends on what you think GT 'is about', I've been playing it since 1998 so I know what it has been about so far and what attracts me to still play it now, but I can see it becoming a lot more.
Offering maps with roads doesn't seem at all far fetched or inappropriate, to me it's only a logical next extension to the whole GT-concept in the first place, in fact I could imagine it already being there in GT1.